Internal combustion engine



Aug. 26, 1941. H. F. BAKEWELL INTERNAL COMBUSTION ENGINE Filed Aug. 5, 1959 2 Sheets-Sheet 1 INVENTOIL HaPc/FQ/ewe, La l MORNEY.

Aug. 26, 1941. H. F. BAKEWELI.

INTERNAL COMBUSTION ENGINE Filed Aug.v 5, 1959 2 sheets-sheet 2 fla' 45d BY L) M k TTORNEY.

Patented ug'. 26, 1941 UNITED STATES PATENT OFFICE 2,253,490 INTERNAL COMBUST-ION ENGINE Harding F. Bakewell, San Marino, Calif. Application August 5, 1939, Serial No. 288,597

(Ci. 12S-56) 17 Claims.

This invention relates to internal combustion engines; and hasfor an object to provide a multiycylinder engine which combines advantages of balanced operation and relatively shallow engine structure, thereby particularly adapting the engine for mounting in the shallow space within a wing of an airplane for driving a propeller whichr projects from the wing.

More particularly, it is an object of the invention to operatively mount any number of cylinders along a drive shaft, with the cylinders projecting from opposite sides of and having their axes in a common plane which is parallel-to the drive shaft. By mounting the cylinders in a common plane, the engine structure is shallow (perpendicularly to said plane) irrespective of the number of cylinders which are mounted along the drive shaft, and by projecting the cylinders from opposite sides of the drive shaft balanced operation is obtained. l

It is a further object of the invention to operatively mount the cylinders in pairs, with the cylinders of each pair projecting from opposite sides of the drive shaft with their axes in the aforesaid common plane which is parallel to the drive shaft, and with the cylinders of each pair having their axes in the same plane transverse to the drive shaft and adapted for simultaneous outward (and inward) piston-travel of each pair of transversely alined cylinders.

It is a still further object ofv the invention to operatively mount the cylinders and adapt each transversely alined pair for relative pistontravel as above described, v with the plurality of transversely alined pairs of cylinders adapted for relative piston-travel so that as the pistons of one transversely alined pair travel in one drection, i. e. inwardly or outwardly, the pistons of another transversely alined pair travel in the opposite direction,

It is a still further object oi the invention to operatively mount two of the transversely alined pairs of cylinders and adapt the same for relative piston-travel as above described, thereby providing a power unit which is a four-cylinder assembly having its cylinders projecting 'from opposite sides of the drive shaft in a common plane which is parallel thereto, with the cylinders adapted for relative piston-travel which provides balanced operation of the unit.

It is a still further object of the invention to operatively mount any number of said power units relative to a common drive shaft, with staggered piston-travel of the umts, i. e. with the pistons of one unit at end of stroke while the pistons of another unit are between ends of stroke.

It is a still further object of the invention to operatively mount a plurality of four-cylinder assemblies one beyond another along a common drive shaft, with the common plane ofthe cylinders ofthe respective units common to all of said units. A multi-cylinder engine comprising any multiple of four-cylinders is thus provided, with the engine relatively shallow (perpendicular to the common plane of the cylinders of the respective units) since the dimension of the engine in said direction ls only that required for mounting all the cylinders withtheir axes in a common plane which is parallel to the drive shaft, irrespective of the number of four-cylinder assemblies ,which are mounted along the drive shaft.

It is a still further object of the invention to operatively mount a pair of the four-cylinder power units relative to a vcommon drive shaft, with the common planes of the cylinders of the respective units at opposite sides of and parallel to the drive shaft, and with the transversely alined pairs of cylinders of one unit in the same planes transverse to thedrive shaft as the transversely alinedv pairs of cylinders of the other unit. An eight-cylinder assembly is thus provided, which is relatively shallow (perpendicular to the common planes of the cylinders of the respective units) since the dimension of the engine in said direction is only that required for mount ing the cylinders of each of the units with their axes in their respective common planes, and the length of the engine is only that requiredfor mounting two banks of the cylinders in respective planes transverse to the drive shaft.

It is a still further object of the invention to operatively mount any number of eight-cylinder assemblies one beyond another along a common drive shaft, with the pair of common planes of the cylinders of the respective eight-cylinder assemblies common to all of said assemblies. A multi-cylinder engine comprising any multiple of eight-cylinders is thus provided, with the engine relatively shallow (perpendicular to the common planes of the cylinders of the respective eight-cylinder assemblies) since the dimension of the engine in said direction is only that required for mounting the cylinders in a pair of said common planes, irrespective of the number of eight-cylinder assemblies which are spaced along the drive shaft.

Further objects of the invention will be readily understood from the following description of the accompanying drawings which illustrate a preferred form which the invention may assume in practice, it being understood that the form which is shown and described is for the purpose of illustration, and that the invention may be modified and is entitled to various forms without departing from the scope of the appended claims.

In the drawings,

Fig. 1 is a plan view of an internal combustion engine constructed in accordance with the invention.

Fig. 2 is a transverse section on the line 2 2 of Fig. 1.

Fig. 3 is a transverse section on the line 3 3 of Fig. 1.

Fig. 4 is a section on the line 4 4 of Fig. 3.

Figs. 5 and 5' 'are diagrams of relative piston travel of the respective four-cylinder units of one of the eight-cylinder assemblies shown at Figs. 1 to 3.

Fig. 6 is a view similar to` Fig. 2, showing a modified construction.

The engine comprises one or more power units, each consisting of four cylinders having their axes in a commonv plane which is parallel to a common drive shaft. The four cylinders are arranged in pairs one beyond the other along the drive shaft, with the cylinders of each pair havlng their axes projecting from opposite sides of the drive shaft in the same plane transverse thereto.

At Fig. l, the cylinders of one of the power units are shown respectively at i, 2, 3 and 4; with the cylinders E 2 projecting from one side of common drive shaft 5 and the cylinders 3 4 projecting from the opposite side of the drive shaft. rIhe cylinders 3 have their axes in plane A A which is transverse to the drive shaft, and the cylinders 2 4 have their axes in'the transverse plane B B which is spaced along the drive shaft from the plane A A, just the distance neces-y sary to permit valve operating mechanism (hereinafter described) being mounted in a transverse plane which is midway between the transverse planes A A and B B. The cylinders I, 2, 3 and il have their axes at right angles to the axis of the drive shaft 5 and in a common plane C C, which plane is parallel io and preferably spaced from the'axis of the drive shaft at one side thereof, preferably above the same, as shown at Fig. 2.

As shown at Fig. 1, each of the pair of cylinders i 3 and 2 4 are adapted for simultaneous outward (and inward) piston-travel, with the piston-travel of the pair of cylinders 2 4 offset 180 with relation to piston-travel of the cylinders i 3. For this purpose, countershafts 6 1 are journaled at the respective sides of the drive shaft 5, parallel to said drive shaft and preferably in the plane C C (Fig. 2); and crank-throws 6 8 and id ii are provided at the respective ends of the shafts 6 1 in alinement with the respective cylinders i, 2, 3 and 4. The crankthrows 8 2 (and the crank-throws in ii) are relatively offset 180, and the crank-throws 8 10 (and the crank-throws i i) are relatively olfset 180.

The construction and arrangement of the countershafts 6 1 and their crank-throws is similar, and therefore only the countershaft 6 will be described in detail. This countershaft is journaled in the engine casing which supports the cylinders l, 2, 3 and 4, at bearings I3 I4 which are spaced longitudinally of the drive shaft 5 between the juxtapositioned cylinders 1 2.

Flywheels i5 |6 are mounted upon the ends of the countershaft which project longitudinally beyond the bearings i3`|4, and the crank-throws 8 9 project longitudinally beyond the outer faces of the respective fiywheels. The crank-throws 8 9 are connected by rods l1 to the pistons I8 of the respective cylinders I 2.

The countershafts 6 1, which are thus respectively driven by the pistons of the cylinders 1 2 and 3 4, are adapted for rotation in the same direction as shown by the arrows D of Fig. 2, and engage the drive shaft 5 for rotating the latter in the direction of the arrow E. For this purpose, gears 20 are fixed on the shafts 6 1 between their bearings l3 l4, and mesh with a gear 2| which is fixed on the drive shaft 5. This gearing is preferably herringbone gearing. Due to the relative positioning of the crank-throws as previously described, when the piston of the cylinder l is at its outer limit of travel the piston of the cylinder 3 is also at its outer limit of travel, and the pistons of the cylinders 2 4 are at their inward limit of travel.

Each cylinder has usual intake and exhaust valves 22 23. Operating mechanism for the valves preferably includes shafts 24 25 which project from opposite sides of the drive shaft 5, in a transverse plane midway between the planes A A and B B, and which are driven respectively by the countershafts 6 1.

The valve operating mechanisms which respectively include the shafts 24 25 are similar, and therefore only the operating mechanism which includes the shaft 24 will be described in detail. The shaft 24 is journaled in bearings 26 of the engine casing and is driven by the countershaft 6 through intermediate gearing. For this purpose, a shaft 21 is journaled in the engine casing at one side of and parallel to the shaft 6, and is driven by the shaft 6 through gearing 28 29. The shaft 21 in turn drives the shaft 24 through bevel gearing 30-31. At its outer end the shaft 24 drives cam shafts 32 through bevel gearing 33 34; and the cam shafts overlie the respective cylinders I 2 and have cams :i5-36 which respectively cooperate with the valves 22-23.

The drive shaft 5 is journaled in bearings lill-4i at the ends of the engine casing; and the cylinders i, 2, 3 and 4, together with their associated parts, constitute a complete power unit comprising a four-cylinder assembly adapted for usual four-cycle operation, preferably with its valve operating mechanism and its ignition system (not shown) timed for firing the cylinders in the order 1-2-3-4 and at intervals of 180 circumferential-ly of the shafts 6 1.

The power unit as thus described has all its cylinders in the plane C C (Fig. 2), thereby providing a four-cylinder assembly which is extremely shallow in a direction perpendicular to said plane. Operation of the unit is balanced, in that the transversely alined pair of cylinders 1 3 and their crank-throws 8 I0 balance one another, i. e. these cylinders are arranged 'for simultaneous outward (and inward) pistontravel; and in similar manner the transversely alined pair of cylinders 2 4 and their crankthrows B ll balance one another.

Each countershaft 6 1 is also balanced, in that the cylinders and crank-throws which are associated with each countershaft balance one another. For example, the cylinders 2 which are associated with the countershaft 6 are arranged for simultaneous piston-travel in opposite directions, i. e. the piston of one of said cylinders is traveling inwardlywhile the piston of the other cylinder'is traveling outwardly.

Driving torque of all the cylinders is exerted vmedially of the length of the drive shaft 5, i. e. at the gear 2l; and said driving torque is exerted on the shaft 5 between its bearings 40'-4I which need be spaced longitudinally of the shaft only sufficient distance to accommodate juxtapositioned cylinders I--2 and 3-4 in planes A-A and B-B between said bearings. Each countershaft 6 1 need only be of a length to aline its crankthrows, which are at the remote ends of the countershaft, with the axes of the juxtapositioned cylinders I-2 and 3-4, and the bearings I3-I4 for each countershaft need only be spaced langitudinally of its shaft sufficient distance to accommodate the gearing -2I, 28-29 and --3I between said bearings.

A power unit as thus described may be assembled within a unitary engine casing so as to form the modification of the invention which is shown at Fig. 6, the, parts which have been previously described being indicated by the same reference numerals with the exponent a. The common plane Cil-CH*` of the cylinders of the unit, and which plane is preferably spaced from the drive shaft 5a at one side thereof as previously described, is preferably at that side of the drive shaft which positions the plane of the cylinders above the drive shaft. A unitary fourcylinder assembly is thus provided; and one of these four-cylinder assemblies may be employed alone or a plurality of said four-cylinder assemblies may be spaced along the drive shaft 5a, with said drive shaft projecting beyond the ends of the engine casing of each of said unitary assemblies and journaled in fixed supports at each end of each engine casing.

When more than one of said four-cylinder assemblies are employed, the cylinders of all the assemblies are in the common plane Cie-Ca. The engine is thus relatively shallow in a direction perpendicular to the plane Cia-Ca, and each assembly is a self-balancing independent power unit with its cylinders adapted for relative piston-travel as previously described. The crankthrows of each of the four-cylinder assemblies are circumferentially offset relative to the crankthrows of the other four-cylinder assemblies, so that the time interval between start of successive flring strokes of one assembly is uniformly divided by start of a firing stroke of each of the other assemblies, e. g. when employing a pair of said four-cylinder assemblies the crankthrows of one assembly are circumferentially offset relative of one assembly are at end of stroke the pistons of the other assembly are midway of their stroke.

In lieu of the four-cylinder assembly shown at Fig. 6, a pair of the four-cylinder units may be assembled within a unitary lengine casing so as to provide an eight-cylinder assembly as shown at Figs. 1 to 3 and as diagrammed at Figs. 5 and 5'. One of these four-cylinder power `units is indicated by the reference numerals previously employed, and corresponding parts of the other power unit are indicated by the same reference numerals, primed.

The drive shaft 5 is common to the pair of power units, the plane C-C of the cylinders I, 2, 3 and 4 being above the drive shaft and the plane C'-C' of the cylinders I', 2', 3 and'4' of the other power unit being spaced the same distance clear one another.

below the drive shaft, with the planes C-C and C'C' parallel as shown at Fig. 2. The transversely alined pair of cylinders I--3 are in the same transverse plane A--A as the pair of transversely alined cylinders I'3' of the other power unit, and in similar manner the transversely alined cylinders 2--4 and 2-4 are in the same transverse plane B-B. The countershafts 6-*1 and 6'-|' are adapted for rotation in lthe same direction indicated by arrows D; and their gears 2li-20', which are in the same transverse plane, mesh with the common gear 2| which is fixed to the drive shaft 5, for rotating the drive shaft in the direction of arrow E. The crank-throws The planes C-C and C'-C' of the cylinders of the eight-cylinder assembly are spaced apart just suflicient distance for the cylinders and driving connections of the pair of power units to The eight-cylinder assembly is thus relatively shallow in a direction perpendicular to the planes C-C and C-C, and its length is only that necessary to accommodate its cylinders in the transverse planes A-A and B-B. Operation is balanced in each power unit as previously described, and the crank-throws of each transversely alined pair of cylinders of one unit are balanced by the crank-throws of that pair of cylinders ,of the other unit which are in the same transverse plane.

The eight-cylinder assembly is housed Within a unitary engine casing; and one of these unitary eight-cylinder assemblies may be employed as a power unit, or a plurality of said eight-cylinder assemblies may be spaced along the drive shaft 5 as shown at Fig. 1, with the drive shaft projecting beyond the ends of the engine casing of each of the eight-cylinder assemblies and journaled in xed supports at each end of each engine casing.

When more than one eight-cylinder assembly is employed, their planes C--C and C'-C' are common to all the assemblies, and each eightcylinder assembly is a self-balancing independent assembly with its cylinders adapted for relative piston-travel as previously described. The crankthrows of each of the eight-cylinder assemblies are circumferentially offset relative to the crankthrows of the other eight-cylinder assemblies, so that the time interval between start of successive ring strokes of one assembly is uniformly divided by start of a firing stroke of each of the other assemblies, e. g. when employing a pair of said eight-cylinder assemblies the crankthrows `of one assembly are circumferentially offset relative to the crank-throws of the other assembly so that when the pistons I, 2, 3 and 4 of one eight-cylinder assembly are at ends of stroke, at which time the cylinders I', 2', 3' and 4' of that assembly are midway of their stroke, the pistons of the other eight-cylinder assembly are at quarter-stroke as indicated by dotted lines at Fig. 1.

With the power plant comprising either one or more 'of the four cylinder assemblies shown at Fig. 6, or one or more of the eight-cylinder assemblies shown at Figs. 1 to 3, the mounting for each cylinder assembly provides fixed bearings for the projecting ends of the drive shaft, and provides a torque mounting for the cylinder as'- sembly relative to the drive shaft, with the torque mounting for the respective cylinder assemblies adapted for limited yielding, independently of one another.

As an instance of this mounting and when` employing eight-cylinder assemblies as shown at Figs. 1 to 3, supporting rods 45 extend longitudinally of the drive shaft 5 at each side thereof and between the cylinders which lie in the respective planes C-C and C-C'. These supporting rods are mounted upon a flxed support (not shown), which in preferred employment of the engine is the frame structure within the wing of an airplane, thereby adapting the relatively shallow engine for mounting in said wing structure, with one end of the drive shaft of the engine projecting outwardly beyond the wing for mounting a propeller thereon.

Outwardly beyond each end of the engine casing of each eight-cylinder assembly, a transverse frame is mounted on the rods 45, and the projecting ends of the drive shaft are journaled in these frames. The transverse frame at the rear end of the rearward eight-cylinder assembly of Fig. 1 is shown at 41. Between the two eight-cylinder assemblies a transverse frame 48 which is common to the two assemblies is preferably employed. 'I'he transverse lframe at the front end of the forward eight-cylinder assembly is shown at 49.

The projecting ends of the drive shaft 5 are journaled in the transverse supporting frames, and the engine casing of each cylinder assembly is journaled relative to the shaft 5 and the transverse supporting frames at the bearings 40-4I, thereby providing a torque mounting for each engine casing relative to the drive shaft.

Each engine casing is supported for limited yielding at its torque mounting. For this purpose, a hydraulic supporting ram is provided between each engine casing and one of its transverse supporting frames. The ram provides hydraulically-cushioned, torque yielding of each engine casing relative to the drive shaft; and a gauge is preferably associated with each ram for indicating driving torque of the corresponding cylinder assembly.

As shown at Figs. 1 to 4, the hydraulic rams 50 for next adjacent eight-cylinder assemblies may be mounted on their common supporting frame 43, and the readings of the gauges for the respective rams may be separately shown upon a common dial 5l.

The end of the drive shaft at the forward end `of the engine is shown as projecting an appreciable distance for reception of a propeller, and is preferably housed within a casing 55 which is fixed relative to the engine casing of the forward cylinder assembly. The transverse supporting frame 49 which is employed at the front end of this cylinder assembly has the drive shaft 5 journaled in said frame as previously described; and the casing 55 surrounds the transversely medial portion of the frame 49, with the projecting ends of said frame extending through apertures in the respective sides of the casing 55.

In the modification of the invention which is shown at Fig. 6, the mounting for each fourcylinder assembly is the same as that described for the eight-cylinder assemblies of Figs. 1 to 4, similar parts being indicated by the same reference numerals with the exponent a. In this case, the supporting rods 45a underlie the cylinder assembly, since the latter has all its cylinders in the one plane C'i-C.

The above described mounting and torque indicating means for the power plant is described and claimed in my copending application Ser. No. 317,690, filed February 7, 1940.

I claim:

1. In an internal combustion engine, a drive shaft, a pair of crank shafts at respective sides of and in a common plane parallel to the drive shaft, driving connections between the respective crank shafts and the drive shaft, a pair of cylinders respectively outwardly projecting at opposite sides of the drive shaft with their axes in said common plane, pistons in the respective cylinders, crank-throws on the respective crank shafts in alinement with the respective cylinders, and connecting rods between the respective pistons and the respective crank-throws, the crankthrows of the pair of crank shafts being relatively offset 180, the aforesaid construction comprising a two-cylinder assembly, and a pair of said twocylinder assemblies having their drive shafts common to said pair of assemblies, with the planes of the cylinders of the pair of assemblies at opposite sides of said common drive shaft and parallel, the crank-throws of the pair of assemblies being relatively offset 2. In an internal combustion engine, a drive Shaft, a pair of crank shafts at respective sides of and in a common plane parallel to the drive shaft, driving connections between the respective crank shafts and the drive shaft, a pair of cylinders respectively outwardly projecting at opposite sides of the drive shaft with their axes in said common plane, the axes of the cylinders being in alinement transversely of the drive shaft, pistons in the respective cylinders, crankthrows on the respective crank shafts in alinement with the respective cylinders, and connecting rods between the respective pistons and the respective crank-throws, the crank-throws of the pair of crank shafts being relatively offset the aforesaid construction comprising a twocylinder assembly, and a pair of said two-cylinder assemblies having their drive shafts common to said pair of assemblies, with the planes of the cylinders of the pair of assemblies at opposite sides of said common drive shaft and parallel, the crank-throws of the pair of assemblies being relatively offset 90.

3. In an internal combustion engine, a drive shaft, a pair of crank shafts at respective sides of and in a common plane parallel .to the drive shaft, driving connections between the respective crank shafts and the drive shaft, the driving connections being in alinement transversely of the drive shaft, a pair of cylinders respectively outwardly projecting at opposite sides of the drive shaft with their axes in said common plane, pistons in the respective cylinders, crank-throws on the respective crank shafts in alinement with the respective cylinders, and connecting rods between the respective pistons and the respective crank-throws, the crank-throws of the pair of crank shafts being relatively offset 180, the aforesaid construction comprising a two-cylinder assembly, and a pair of said two-cylinder assemblies having their drive shafts common to said pair of assemblies, with the planes of the cylinders of the pair of assemblies at opposite sides of said common drive shaft and parallel, the crank-throws of the pair of assemblies being relatively offset 90.

shaft, a pair of crank shafts at respective sides of and in a common plane parallel to the drive shaft, driving connections between the respective cranks shafts and. the drive shaft, the driving connections being in alinement transversely of the drive shaft, a pair of cylinders respectively outwardly projecting at opposite sides of the drive shaft with their axes in said common plane, the axes of the cylinders being in alinement transversely of the drive shaft, pistons in the respective cylinders, crank-throws on the respective crank shafts in alinement with the respective cylinders, and connecting rods between the respective pistons and the respective crankthrows, the crank-throws of the pair of crank shafts being relatively offset 180, the aforesaid construction comprising a two-cylinder assembly, and a pair of said two-cylinder assemblies having,r their drive shafts common to said pair of assemblies, with 'the planes of the cylinders of the pair of assemblies at opposite sides of said common drive shaft and parallel, the crank-throws of the pair of assemblies being relatively offset 90.

5. In an internal combustion engine, a drive shaft, a pair of crank shafts at respective sides of and in a common plane parallel to the drive shaft,

and connecting rods between the respective pis- A tons and the respective crank-throws, the crankthrows which are in alinement with each of the said pairs of cylinders being relatively offset 180, and the crank-throws of each crank shaft being uniformly offset circumferentially of said crank shaft.

6. In an internal combustion engine, a drive shaft, a pair of crank shafts at respective sides of and in a common plane parallel to the drive shaft, driving connections between the respective crank shafts and the drive shaft, the driving connections being in alinement transversely of the drive shaft,'two pairs of cylinders spaced along the drive shaft with the axes of the cylinders of each pair respectively outwardly projecting at opposite sides and in alinement transversely of the drive shaft, the axes of all the cylinders being in said common plane, pistons in the respective cylinders, a pair of crankthrows on each crank shaft, the crank-throws of the crank shaft which is at each side of the drive shaft being in alinement with the respective cylinders which are at the same side of the drive shaft, and connecting rods between the respective pistons and the respective crank-throws, the crank-throws which are in alinement with each of the said pairs of cylinders being relatively offset 180., and the crank-throws of each crank shaft being relatively offset 180.

7. In an internal combustion engine, a drive shaft, a pair of crank shafts at respective sides of and in a common plane parallel to the drive shaft, driving connections between the'respective crank shafts and the drive shaft, the driving connections being medially of the length of the crank shafts and in alinement transversely of the drive shaft, two pairs of ,cylinders spaced along the drive shaft with the axes of the cylinders of each pair respectively outwardly projecting at opposite sides and in alinement transversely of, the drive shaft, the axes of all the cylinders being in said common plane, pistons in the respective cylinders, iiywheels at the respective ends of each crank shaft, bearings for each crank shaft between its medial driving connection and'its respective ywheels, crank-throws projecting from the outer faces of the respective flywheels, the crank-throws of the crank shaft which is at each side of the drive shaft being in alinement with the respective cylinders which are at the same side of the drive shaft, and connecting rods between the respective pistons and the respective crank-throws, the crank-throws which are in alinement with each of the said pairs of cylinders being relatively offset and the crankthrows of each crank shaft being relatively ofi'- set 180. l

8. In an internal combustion engine. a drive shaft, a pair of crank shafts at respective sld-es of and in a common plane parallel tothe drive shaft, driving connections'between the respective crank shafts and the drive shaft, two pairs of cylinders spaced along the drive shaft with the axes of the cylinders of each pair respectively outwardly projecting at opposite sides and in alinement transversely of the drive shaft, the axes of all the cylinders being in said common plane, pistons in the respective cylinders, a pair of crank-throws on each crank shaft, the crankthrows of the crank shaft which'is at each side of the drive shaft being in alinement with the respective cylinders which are at the same side of the drive shaft, connecting rods between the respective pistons and the respective crankthrows, and an operating mechanism for the valves of the cylinders which are at each side of the drive shaft, each valve' operating mechanism including a shaft projecting outwardly in a plane between the cylinders which are at one side of the drive shaft, and a driving connection between said shaft and the crank shaft which is at the same side of the drive shaft.

9. In an internal combustion engine, a drive shaft, a pair of crank shafts at respectivesides of and in a common plane parallel to the drive shaft, driving connections between the respective crank s.1afts and the drive shaft. pairs of cylinders spaced along the drive shaft with thercylinders of each pair respectively outwardly projecting at opposite sides of the drive shaft, the axes of all the cylinders being in said common plane, pistons in the respective cylinders, a plurality of crank-throws on each crank shaft, the crank-throws ofthe crank shaft whichis at each side of the drive shaft being in alinement with the respective cylinders at the same side of the drive shaft, connecting rods between the respective pistons and the respective crank-throws, the crank-throws which are in alinement with each of the said pairs of cylinders being relatively offset 180, and the crank-throws of each crank shaft being uniformly offset circumferentially of said crank shaft, the aforesaid construction comprising a unitary cylinder assembly, and a plurality of said cylinder assemblies having their drive shafts forming a longitudinal continuation of a common drive shaft, with the cylinders of said assemblies in the same common plane and with the crank-throws of the plurality of assemblies relatively circumferentially offset so that the time interval between start of successive ring strokes of one assembly is uniformly divided by start of a firing stroke of each of the other assemblies.

10. In an internal combustion engine, a drive shaft, a pair of crank shafts at respective sides of and in a common plane parallel to the drive shaft, driving connections between the respective crank shafts and the drive shaft, the driving connections being in alinement transversely of the drive shaft, two pairs of cylinders spaced along the drive shaft with the axes of the cylinders of each pair respectively outwardly projecting at opposite sides and in alinement transversely of the drive shaft, the axes of all the cylinders being in said common plane, pistons in the respective cylinders, a pair of' crankthrows on each crank shaft, the crank-throws of the crank shaft which is at each side of the drive shaft being in alinement with the respective cylinders which are at the same side of the drive shaft, connecting rods between the respective pistons and the respective crankthrows, the crank-throws which are in alinement with each of the said pairs of cylinders being relatively voffset 180, the crank-throws of each crank shaft being relatively offset 180, the aforesaid construction comprising a power unit, and a pair of said units mounted with their drive shafts common to said pair of ,units and with the common planes of the cylinders of the respective units at opposite sides of said common drive shaft and parallel, the crank-throws of the pair of units being relatively offset 90.

11. In an internal combustion engine, a drive shaft, a pair of crank shafts at respective sides of and lin a common plane parallel to the drive shaft, driving connections between the respective crank shafts and the drive shaft, the driving connections being in alinement transverselyv of the drive shaft, two pairs of cylinders spaced along the drive shaft with the axes of the cylinders of each pair respectively outwardly projecting at opposite sides and in alinement transversely of the drive shaft, the axes of all the cylinders being in said common plane, pistons in the respective cylinders, a pair of crankthrows on each crank shaft, the crank-throws of the crank shaft which is at each side of the drive shaft being in alinement with the respective cylinders which are at the same side of the drive shaft, connecting rods between the respective pistons and the respective crank-throws, the crank-throws which are in alinement with each of the said pairs of cylinders being relatively offset 180, the crank-throws of each crankshaft being relatively offset 180, the aforesaid construction comprising a power unit, a pair of said units mounted with their drive shafts common to said pair of units and with the common planes of the cylinders of the respeetive units at opposite sides 0f said common drive shaft and parallel, the crank-throws of the pair of units being relatively offset 90, the aforesaid construction comprising aunitary cylinder assembly, and a plurality of said cylinder assemblies having their drive shafts forming a longitudinal continuation of a commondrive shaft, with the cylinders of said assemblies in the same pair oi common planes and with the crank-throws of the plurality of assemblies rela- -tively circumferentially offset so that the time interval between start of successive firing strokes of one assembly is uniformly divided by start of a firing stroke of each of the other assemblies. 12. In an internal combustion engine, a drive shaft, a pair of crank shafts at respective sides of and in a common plane parallel to the drive shaft, driving connections between the respective crank shafts and the drive shaft, the driving connections being medially of the length of the crank shafts, two pairs of cylinders spaced along the drive shaft with the axes of the cylinders of each pair respectivelyoutwardly projecting at opposite sides of the drive shaft, the axes of all the cylinders being in said common plane, pistons in the respective cylinders, a pair of crank-throws on each crank shaft, the crankthrows of the crank shaft which is at each side of the drive shaft being in alinement with the respective cylinders which are at the same side of the drive shaft, connecting rods between the respective pistons and the respective crankthrows, and bearings for each crank shaft between its medial driving connection and its respective crank-throws, the crank-throws which are in alinement with each of the said pairs of cylinders being relatively offset 180.

13. In an internal combustion engine, a drive shaft, a pair of crank shafts at respective sides of and in a common plane parallel to the drive shaft, driving connections between the respective crank shafts and the drive shaft, the driving connections being medially of the length of the crank shafts, two pairs of cylinders spaced along the drive shaft with the axes of the cylinders of each pair respectively outwardly projecting at opposite sides 0f the drive shaft, the axes of all the cylinders being in said common plane. pistons in the respective cylinders, nywheels at the respective ends of each crank shaft, bearings for each crank shaft between its medial driving connection and its respective fiywheels, crank-throws at the respective iiywheels, the

crank-throws of the crank shaft which is at each side of the drive shaft being in alinement with the respective cylinders which are at the same side of the drive shaft, and connecting rods between the respective pistons and the respective crank-throws.

14. In an internal combustion engine, a drive shaft, a pair of crank shafts at respective sides of and in a common plane parallel to the drive shaft, driving connections between the respective crank shafts and the drive shaft, two pairs of cylinders spaced along the drive shaft with the axes of the cylinders of each pair respectively outwardly projecting at opposite sides of the drive shaft, the axes of all of the cylinders being in said common plane, pistons in the respective cylinders, a pair of crank-throws on each crank shaft, the crank-throws of the crank shaft which is at each side of the drive shaft being in alinement with the respective cylinders which are at the same side of the drive shaft, connecting rods between the respective pistons and the respective crank-throws, an operating mechanism for the valves of the cylinders which are at each side of the drive shaft, each valve operating mechanism projecting outwardly in a plane between the cylinders which -are at one side of the drive shaft, and means at the innerA engine.

spective crank-throws,

i projecting at opposite sides of the drive shaft, `the axes of all the cylinders being in said common plane, pistons in the respective cylinders, a plurality of crank-throws on each crank shaft, the crank-throws of the crank shaft which is at each side of the drive shaft being in alinement with the r-espective cylinders which are at the same side of the drive shaft, connecting rods between the respective pistons and the rethe aforesaid construction comprising a unitary cylinder assembly, and a pluralitir of said cylinder assemblies having their drive shafts forming a longitudinal continuation of a common drive shaft, with the cylinders of said assemblies in the same common plane and with the crank-throws of the plurality' of assemblies relatively circumferentially offset so that the time interval between start of successive firing strokes of one assembly is uniformly divided by start of a ring stroke of each of the other assemblies.

16. In an internal combustion engine, a drive shaft, a pair of crank shafts at respective sides of and in a common plane parallel to the drive shaft, driving connections between the respective crank shafts and the drive shaft, pairs of cylinders spaced along the drive shaft with the cylinders of each pair Vrespectively outwardly projecting at opposite sides of thedrive shaft. the axes of all thecylnders being in said common plane, pistons in the respective cylinders, a plurality of crank-throws on' each crank shaft, the crank-throws of the crank shaft which is at each side of the drive shaft being in alinement with the respective cylinders which are at the same side of the drive shaft, connecting rods between the respective pistons and the re spective crank-throws, the aforesaid construction comprising a power unit, and a pair of said units mounted with their drive shafts common to said pair of units and with the common planes of the cylinders of the respective units at opposite sides of said common drive shaft and parallel, the crank-throws of the pair of units being relatively offset 90.

1'7. In an internal combustion engine, a drive shaft, a. pair of crank shafts at respective sides of and in a. common plane parallel to the drive shaft, driving connections between the respective crank shafts and the drive shaft, pairs of cylinders spaced along the drive shaft with the cylinders of each pair respectively outwardly projecting at opposite sides of the drive shaft, the axes of all the cylinders being in said common plane, pistons in the respective cylinders, a plurality ofcrank-throws. on each crank shaft, the crank-throws ofthe crank shaft which is at each side of the drive shaftbeing in alinement with the respective cylinders which -are at the same side of the drive shaft, connecting rods between the respective pistons and the respective crank-throws, the aforesaid construction comprising a power unit, and a pair of said units mounted with their drive shafts common to said pair of units and with the common planes of the cylinders vof the respective units at opposite sides of said common drive shaft and parallel, the crank-throws of the pair of units being relatively oiset 90, the aforesaid construction comprising a unitary cylinder assembly, and

a. plurality of said cylinder assemblies having their drive shafts forming a longitudinal continuation of a common drive shaft, with the cylinders of said assemblies in the same pair of common planes and with the crank-throws of the plurality of assemblies relatively circumferentially oifset so that the time interval between start of successive ring strokes of one assembly is uniformly divided by start of a firing stroke of leach of the other assemblies.

HARDING F. BAKEWELL. 

